As far as I know, varied surfactants are utilized in EOR; including anionic, non-ionic, and cationic surfactants. Depending on the type of reservoirs, desired surfactants are chosen.
Take sandstone reservoirs as an example; it has been reported that anionic surfactants would be the best choice in the mentioned type of reservoirs.
I highly recommend you to read the below paper which is come in handy concerning your question:
""Most common surfactants employed in chemical enhanced oil recovery""
I would recommend you our idea of using hydrotropes (waste) for enhanced oil recovery. Hydrotropes (lower surfactants) in the presence of oil (hydrocarbons) behave like typical surfactants. In the hydrotrope-water-oil system, the hydrocarbon is completing the hydrocarbon chain of the hydrotrope. They reduce the oil / water interfacial tension.You may find your hydrotropes that are not yet recycled.
I would say if you go through the literature paper, Many research articles have used SLS, SDS for anionic surfactant; Tween 80, Triton X-100 for non-ionic surfactant and CTAB for cationic surfactant. You can come across several modified surfactants through the research paper.